THE THYMUS GLAND 1 17 



The results obtained by R. Fischl from his experiments with 

 goats, rabbits and dogs were purely negative, and he concludes 

 from this that the removal of the thymus has no effect upon the 

 development of the subject. Basch, however, is of the opinion 

 that Fischl 's experiments were carried out under quite wrong 

 conditions, and for this reason cannot be regarded as con- 

 clusive. 



Basch points out that the method of extirpation practised by 

 Friedleben, and by the greater number of investigators after him, 

 that, namely, of removing the thymus by way of the suprasternal 

 fossa, is not a good one, at any rate in the case of dogs. He 

 preferred a median section of the sternum, and was careful to 

 assure himself before finishing the operation that every particle of 

 the thymus had been removed. Post-mortem examination some 

 time after operation does not yield the same results as the 

 exploration of the living animal. The almost inevitable pneumo- 

 thorax does not, in his experience, produce unfavourable results. 

 Of the animals upon which he operated (frogs, doves, rabbits, 

 cats, guinea-pigs, dogs), dogs are most sensitive to the removal 

 of the thymus. As in dogs the thymus continues to develop only 

 during the first weeks after birth, and, at the second month 

 undergoes rapid involution, Basch always employed suckling dogs 

 for his experiments, from the same litter as control animals. In 

 seventeen out of twenty litters, he succeeded in keeping at least 

 one subject and one control animal alive for longer than four 

 weeks. He destroyed the greater number of the animals operated 

 upon in the second month after extirpation ; a few were kept 

 for a longer period and, in one instance, the animal was kept for 

 six months. 



The most important changes which Basch observed in his 

 thymectomized dogs were those affecting the skeleton. From the 

 second to third week after operation the bones were generally 

 distinctly softer and more pliable than in the control animals, and 

 the thymectomized animals were more straddling and awkward in 

 their gait. The hinder part of the body was weaker and more 

 emaciated, and the upper and lower legs were turned outwards ; 

 there was less liveliness of movement than in the control animal, 

 the thymectomized animal mostly sitting upon its haunches. A 

 few weeks later, the front legs also became bandy ; there was a 

 broadening in the region of the lower radial epiphysis ; and the 

 animal walked on the flat of its feet. The animals were backward 

 in development as compared with the control animals, and some- 

 times showed a change in the mental condition ; there was less 

 movement and less intelligence. There was, moreover, in the 

 course of the first and second months, a distinct backwardness 

 in weight. 



In order to test the conditions of ossification, Basch fractured 

 a leg-bone at the same time and under similar conditions in both 



